These are possible side effects for Black Cohosh, each herb that is used for menopause would have different effects. It may not be advisible to use convential and alternative menopause treatments together.
Since Black Cohosh can lower blood pressure antihypertensives and this herb shouldn't be used together.
Though it has virtually no toxic effects, black cohosh may cause stomach upset in certain people. One study suggested that it may induce slight weight gain and dizziness in some women. It may also lower blood pressure. a very high dose can cause nausea, vomiting, reduced pulse rate, heavy perspiration, and headache.
HTH.
Joonybug